The statements in this section merely provide background information related disclosure and may not constitute prior art.
Typically NOx adsorber or NOx trap (also called Lean NOx trap, abbreviated LNT) is a device that is used to reduce nitrogen oxides (NO and NO2) emissions from a lean burn internal combustion engine by means of adsorption.
Typically the lean burn engines, particularly diesel engines, present a special challenge to emission control system engineers because of the relatively high levels of O2 (atmospheric oxygen) in the combustion. Because of NOx emissions from diesel engines, technologies such as exhaust gas recirculation (EGR) and selective catalytic reduction (SCR) have been used. However EGR is of limited effectiveness and SCR requires a continuous supply of reductant to the exhaust.
The so called NOx trap is used to support the NOx-aftertreatment while operation of the combustion engine.
In the past various concepts have been designed to “purge” or “regenerate” the NOx trap, whereby the use of fuel as reactants was used, for example diesel fuel. Changing an injection pattern of the combustion engine can be used to purge the NOx trap. The NOx trap can be configured to desorb and react with hydrocarbons under rich conditions to produce water and nitrogen which in general are not harmful for the environment. However, these concepts requires in general additional fuel.
Document U.S. Pat. No. 6,779,339 B1 relates to a method of treating a fuel lean exhaust containing NOx and SO2. The method includes splitting the exhaust into major and minor portions for flow through multiple flow paths each of which contains a particulate trap and an absorber containing a NOx oxidation catalyst and a nitrate absorbent.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.